"This suggests that over the past five years, nearly one-third of the growing population of baby-boomer owners and others who wanted to sell their businesses have been unable to do so," said Peter Siegel, founder and president of BizBen.com.

Santa Rosa was the most active market, with 35 of the transactions in the quarter. Other active markets were in Healdsburg and Petaluma, where there were six deals in each city.